Several extracellular heparin-binding proteins involved in regulation of growth and differentiation belong to a new family of growth factors. These growth factors are highly related proteins of about 140 amino acids that contain 10 conserved cysteines probably involved in disulphide bonds, and include pleiotrophin [15121180] (also known as heparin-binding growth-associated molecule HB-GAM, heparin-binding growth factor 8 HBGF-8, heparin-binding neutrophic factor HBNF and osteoblast specific protein OSF-1); midkine (MK) [15047154]; retinoic acid-induced heparin-binding protein (RIHB) [7796887]; and pleiotrophic factors alpha-1and -2 and beta-1 and -2 from Xenopus laevis, the homologs of midkine and pleiotrophin respectively. Pleiotrophin is a heparin-binding protein that has neurotrophic activity and has mitogenic activity towards fibroblasts. It is highly expressed in brain and uterus tissues, but is also found in gut, muscle and skin. It is thought to possess an important brain-specific function. Midkine is a regulator of differentiation whose expression is regulated by retinoic acid, and, like pleiotrophin, is a heparin-binding growth/differentiation factor that acts on fibroblasts and nerve cells.

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry
out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 2 models
in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical
are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have
different domain combinations including a Midkine domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

There are 2 hidden Markov models representing the Midkine superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.